Raphael josia



'rurnn STATES ATEN'I rrrcn.

RAPHAEL JOSIA, OF FLORENCE, ITALY, ASSIGNOR TO WILLIAM REY AND C. DE VARIGNY, BOTH OF PARIS, FRANCE.

COMPOSITION FOR TREATING SULPHATES 0F LIME FOR THE MANUFACTURE OF ARTIFICIAL MARBLE.

SPECIFICATION forming part of Letters Patent No. 265,511, dated October 3, 1882,

Application filed August 9, 1882.

To all whom it may concern:

Be it known that l, RAPHAEL JOSIA, ofFlorence, Kingdom of Italy, have invented or discovered a new and useful Improvement in Gompositions for Treating Sulphates of Lime for the Manufacture ofArtificial Marble; and I do hereby declare the following to be a full, clear, concise, and exact description thereof.

In an application for Letters Patent of the United States filed March 2, 1882, I have described and made claim to an improved process of treating; or preparing gypsum (calcic sulphate or sulphate of lime) in the making of articles ofa material which I have termed certaldite, without pulverizatiou of the gypsum. In said application I described briefly certain of the compounds or compositions which I employ to produce certain effects and the manner of using them, but stated that separate applications would be made for patents for such compositions.

The present application relates to one ofthe compositions so referred to, and it is designed for use in the process herein described in the making of lilac-colored ccrtaldite.

In carrying out the process referred to a suitable piece'of gypsum (calcic sulphate) is first formed intothe desired shape, or approximately such, by the use of suitable well-known tools. The gypsum employed may be the ordiuary native gypsum of commerce, though I prefer that which is comparatively pure orfree froin other matters of different composition. Such gypsum is usually obtained hydrated or containing a certain percentage of water in its composition, and the second step in the operation has reference to depriving the gypsum under treatment of a considerable part or the whole of such water. This is done by subjecting it to the action of a gradually-increasing heat, Varying by preference with the size and quality of the material from 260 to 300 Fahrenheit, for about twelve hours, or until the desired partial or complete dehydration is obtained. The length of time as well as the degree of heat required to effect this result will vary somewhat with the size, character, and purity of the gypsum employed, but the temperatures should not exceed 500 Fahrenheit, and both it and the time of exposure (No specimens.)

should be regulated and limited with reference to securing uniformity of treatment throughout the whole mass or body. This operation may be known to bccomplete when a fracture of a tcst block presents a uniform white color. Any suitable drying or baking apparatus may be employed for this purpose, many such being known in kindred branches of the arts; but it should be of such construction that the material under treatment shall not be broughtinto direct contact with the tire. When the desired dehydration has been effected the furnace is allowed to cool gradually, in order that the material under treatment may be cooled gradually; or the material may be removed with due care to prevent breaking and exposure to moisture and allowed to cool outside the furnace gradually until it is reduced in temperature sufficiently to permit handling with safety in its subsequent treatment, which is designed to impart to it the desired color or tint and a high degree of insolubility and hardness throughout its mass. This step involves the use of the composition which forms the subject-matter of invention in the present application. This composition is formed of the following elements: water, by weight, two hundred parts; alum, by weight, four. to five parts; oxalic acid, by weight, two to two and a half parts; Gampeachy wood, by weight, eight parts; carbonate of soda, by weight, five to ten parts. These ingredients, being mixed in about the proportions named, form a solution which is used as a bath, and to this end a suitable quantity of it is placed in a vessel of proper shape to receive the article to be treated, which is dipped or immersed in the bath and subjected to its action until the article has acquired the desired degree of hardness and color. The length of time required to effect this result will depend somewhat on the strength of the ingredients composing the bath or solution, the porosity and nature or physical and chemical condition of the article, but usually twelve hours (more or less) will suffice, though to secure uniformity of treatment and of result through the whole body or mass of the article I prefer repeateddippingstwo, three, or more--say two or three seconds at first and increasing gradually to one, two,

three, or more minutes, more or less, with drying intervals oflike increasinglength between dippings, for half or three quarters of an hour or so, after which the article may remain in the bath fortwelve hours or so.

\Vhile I do not limit my invention by any particular theory of chemical or physical reactions involved in the use of this bath, as above described, I believe, with my present knowledge, that the salt (alum) held in solution by taking the place of the molecules of water displaced by the previous dehydrating operation, acts chemically or physically upon the calcic sulphate and renders it more compact, harder, and less soluble, and thatthe oxalic acid of the bath acts chemically or physically upon the impurities or matters of other composition. (carbonates, &c.,) which are usually contained in greater or less quantities in native gypsums, and produces a like indurating effect upon them, though the alum may have an indurating action upon the impurities present, and the acid may actin like manner more or less upon the calcic sulphate. The Oampeachy wood of the bath acts as acoloiing agent, and the carbonateot' soda is employed iirinci'pally to neutralize the oxalic acid and prevent it from imparting a reddish tinge to the color obtained. Consequently the quantity ot'carbonate of soda employed should be determined with reference to the amount and strength of the acid of the bath; but I believe the limits above given to be the best for ordinary conditions. Since the function of the carbonate of soda is principally to neutralize the coloring tendency of the acid, other well-known forms of alkalies (preferably salts) may be employed as the equivalent of soda, and such substitution of equivalent alkaline compounds I consider as coming within my invention. By the use of this bath a beautiful lilac color is obtained, which will usually be variegated somewhat by lines, veins, or markings ofdarker shades, due probably to impurities present in the caleic sulphate, thus giving the article a beautiful and highly-ornamental appearance. A degree of hardness, compactness, insolubility, and susceptibility of polish is also secured by the use of this bath, which renders the article (certaldite) an excellent and valuable substitute for marbles, ornamental stones, tiles, &c., in the various uses to which they are applied in the arts.

YVhen the article has been treated in the bath, as above described, it is removed and subject-matter of the first application herein referred to. Neither do I limit my present invention to the particular way herein described of applying it, though I now believe this way or process to be the best. I also believe the proportions ofingredients which I have named in forming my improved composition to be the best for the purposes stated, and, among others, to secure a uniform degree of hardness and color throughout the mass of the article. If the solution be very strong, there is great danger of rendering the surface of the article hard very quickly, and thereby preventing proper action of the bath upon the interiorsubstance of the article; or if the solution be very weak too much time is I( quired, and even then a proper degree of hardness, density, and insolubility is not secured; also, by the conjoint action of all the elements of the bath much better results are secured, especially upon native gyp sums, than by a solution formed of a part of the elements. For these reasons I prefer to employ all the elements of the composition in substantially the proportions named; but such limits, though afi'ording the best results, may be varied or exceeded somewhat and still obtain favorable results under skillful manipulation, and all such modificationsemploying the elements substantially as herein described, in about the proportions set forth, I consider as coming within my invention'and claim.

I claim as my invention- The composition herein described for treating dehydrated gypsum, consisting substatr tially of the following elements: water, alun, oxalic acid, Oampeachy wood, and carbonate of soda, in about the proportions set forth.

In testimony whereot'I have hcreuntoset my hand.

tAPHAEL JOSIA.

Witnesses:

GUIDo PANTALIONY, 1%. H. WIIrr'rLEsEY. 

